Angewandte Chemie International Edition

Cover image for Vol. 43 Issue 7

February 6, 2004

Volume 43, Issue 7

Pages 765–909

    1. Cover Picture: Antifreeze Glycoproteins: Elucidation of the Structural Motifs That Are Essential for Antifreeze Activity (Angew. Chem. Int. Ed. 7/2004) (page 765)

      Yuki Tachibana, Garth L. Fletcher, Naoki Fujitani, Sakae Tsuda, Kenji Monde and Shin-Ichiro Nishimura

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200490013

      Antifreeze glycoproteins (AFGPs) found in the body fluids of polar fish are known to protect them from freezing by suppressing ice-crystal growth. The essential structural motifs of AFGPs were revealed by using a combination of chemical synthesis and spectroscopic analysis. The amphiphatic AFGPs form a threefold left-handed axis, which enables the sugar moieties to cluster on one side of the molecule. For further details see the Communication by S.-I. Nishimura and co-workers on page 856 ff.

    2. Speeding Up Biomolecular NMR Spectroscopy (pages 782–786)

      Bernd Simon and Michael Sattler

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200301680

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      A useful acquisition: Reducing the dimensionality of multidimensional NMR experiments dramatically decreases measurement times. Where signal-to-noise is not limiting, GFT NMR spectroscopy (see picture) provides a general scheme for fast data acquisition which can speed up NMR-based protein-structure determination.

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      Industrial Methods for the Production of Optically Active Intermediates (pages 788–824)

      Michael Breuer, Klaus Ditrich, Tilo Habicher, Bernhard Hauer, Maria Keßeler, Rainer Stürmer and Thomas Zelinski

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200300599

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      Of fundamental importance for the pharmaceutical industry is the large-scale availability of enantiomerically pure intermediates, such as amino acids, amino alcohols, amines, alcohols, and epoxides. In this Review industrially relevant syntheses of such intermediates are presented, based on chemical as well as enzymatic and fermentation processes (see scheme).

    4. Glyco-SeS: Selenenylsulfide-Mediated Protein Glycoconjugation—A New Strategy in Post-Translational Modification (pages 828–833)

      David P. Gamblin, Philippe Garnier, Sander van Kasteren, Neil J. Oldham, Antony J. Fairbanks and Benjamin G. Davis

      Version of Record online: 21 JAN 2004 | DOI: 10.1002/anie.200352975

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      Site-selective glycosylation by Se[BOND]S-mediated ligation has led to the efficient formation of a wide variety of conjugates 1 without the need for a large excess of the carbohydrate reagent. By this convergent method it was possible to introduce a heptasaccharide glycan selectively, and to perform a multiple site-selective chemical glycosylation of protein. A chemically Cys-glycosylated glycoprotein was elaborated enzymatically.

    5. Models of High-Valent Intermediates of Non-Heme Diiron Alkane Monooxygenases: Electronic Structure of a Bis(μ-oxo)diron(IV) Complex with Locally Low-Spin Metal Centers (pages 834–838)

      Abhik Ghosh, Espen Tangen, Emmanuel Gonzalez and Lawrence Que Jr.

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200351768

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      Insight into the electronic structures of high-valent intermediates with the {FeIV2(μ-O)2} “diamond core” is provided by density theory calculations. These electronic structures are contrasted with nitrido-bridged heme dimers that contain metal centers with the same oxidation state. Such diamond-core intermediates might actually occur in the catalytic cycles of diiron alkane monooxygenases such as AlkB.

    6. Synthesis, Structure, and [60]Fullerene Complexation Properties of Azacalix[m]arene[n]pyridines (pages 838–842)

      Mei-Xiang Wang, Xiao-Hang Zhang and Qi-Yu Zheng

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200351975

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      Remarkably stable C60and C70complexes with stability constants Ks of 70 680±2060 and 136 620±3770 M−1, respectively, are formed by azacalix[4]arene[4]pyridine 1. The smaller-ring-homologue azacalix[2]arene[2]pyridine and compound 1 were readily synthesized, and they adopt a heavily twisted 1,3-alternate and a 1,2,3-partial cone conformation, respectively, in the solid state (see picture).

    7. Stochastic Detection of Monovalent and Bivalent Protein–Ligand Interactions (pages 842–846)

      Stefan Howorka, Joonwoo Nam, Hagan Bayley and Daniel Kahne

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200352614

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      Single-molecule study on multivalency: The binding kinetics of a tetravalent lectin can be examined at the single-molecule level by using an engineered protein pore carrying up to seven carbohydrate ligands. The binding of the lectin to the pore (see molecular model) produces short and long reversible blockades in single-channel current recordings, which are interpreted as monovalent and bivalent binding events, respectively.

    8. Enantioselective Catalytic Allylation of Carbonyl Groups by Umpolung of π-Allyl Palladium Complexes (pages 846–849)

      Giuseppe Zanoni, Serafino Gladiali, Alberto Marchetti, Paolo Piccinini, Ilenia Tredici and Giovanni Vidari

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200352743

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      Diethylzinc mediates the asymmetric allylation of aldehydes through Umpolung of a π-allyl palladium complex. An investigation of the palladium source and the chiral monophosphane ligands have shown that the leaving group has a dramatic effect on the enantioselectivity of the reaction. The procedure furnished products in satisfactory yields and up to 70 % ee (see scheme).

    9. Rational Design of an Enneanuclear Copper(II) Complex with a Metallacyclophane Core (pages 850–852)

      Xavier Ottenwaelder, Joan Cano, Yves Journaux, Eric Rivière, Conor Brennan, Martine Nierlich and Rafael Ruiz-García

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200352851

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      A hexakis-bidentate building block: Tricopper(II) and enneacopper(II) 1,3,5-metallacyclophanes were synthesized by a combination of self-assembly and a rational approach (see scheme). Both complexes exhibit ferromagnetic coupling in the core, through a spin-polarization mechanism.

    10. Production of an Ultra-Long-Lived Charge-Separated State in a Zinc Chlorin–C60 Dyad by One-Step Photoinduced Electron Transfer (pages 853–856)

      Kei Ohkubo, Hiroaki Kotani, Jianguo Shao, Zhongping Ou, Karl M. Kadish, Guolin Li, Ravindra K. Pandey, Mamoru Fujitsuka, Osamu Ito, Hiroshi Imahori and Shunichi Fukuzumi

      Version of Record online: 22 JAN 2004 | DOI: 10.1002/anie.200352870

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      Long live the state! Photoexcitation of a zinc chlorin–fullerene dyad with a short linkage results in the formation of the ultra-long-lived charge-separated (CS) state by a one-step photoinduced electron transfer without loss of energy, which is inevitable for charge separation by multistep electron-transfer processes. The lifetime of the charge-separated state was 120 s in frozen PhCN at −150 °C (see picture).

    11. Antifreeze Glycoproteins: Elucidation of the Structural Motifs That Are Essential for Antifreeze Activity (pages 856–862)

      Yuki Tachibana, Garth L. Fletcher, Naoki Fujitani, Sakae Tsuda, Kenji Monde and Shin-Ichiro Nishimura

      Version of Record online: 22 JAN 2004 | DOI: 10.1002/anie.200353110

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      Good for winter: The structure–activity relationships of antifreeze glycoproteins (AFGPs) have been characterized by chemical synthesis and conformational analysis. The results revealed that the mode of glycosylation on the threonyl residue in the tripeptide unit is of primary importance in the formation of the specific structure for the antifreeze activity (see picture for the structural requirements of AFGPs).

    12. Disclosing New Inhibitors by Finding Similarities in Three-Dimensional Active-Site Architectures of Polynuclear Zinc Phospholipases and Aminopeptidases (pages 862–865)

      Albert González-Roura, Isabel Navarro, Antonio Delgado, Amadeu Llebaria and Josefina Casas

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200352241

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      Shaping up for inhibition: Identification of three-dimensional structural similarities (see picture) between the active sites of zinc dinuclear aminopeptidases and trinuclear phospholipase C hydrolytic enzymes that are not related by sequence or tertiary structure led to the discovery of phospholipase C inhibition by α-aminohydroxamic acids, a typical family of aminopeptidase inhibitors.

    13. A Highly Efficient Synthesis of Lamellarins K and L by the Michael Addition/Ring-Closure Reaction of Benzyldihydroisoquinoline Derivatives with Ethoxycarbonyl-β-nitrostyrenes (pages 866–868)

      Poonsakdi Ploypradith, Chulabhorn Mahidol, Poolsak Sahakitpichan, Siriporn Wongbundit and Somsak Ruchirawat

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200352043

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      Alkaloid achievement: Lamellarins, a new class of potential nontoxic inhibitors of HIV-1 integrase that are also responsible for multidrug-resistance reversal in cancer cell lines, could be synthesized in three chemical steps and in 60 % overall yields from two simple starting materials (see scheme). The key step in the convergent synthetic approach involved the novel Michael addition/ring-closure reaction to give the pyrrole core and the ester group required for subsequent lactonization in one step.

    14. Remote Substituents Controlling Catalytic Polymerization by Very Active and Robust Neutral Nickel(II) Complexes (pages 869–873)

      Martin A. Zuideveld, Peter Wehrmann, Caroline Röhr and Stefan Mecking

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200352062

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      Remote control: Substituents strongly affect the catalytic properties of complexes 1 in ethylene polymerization, despite their remoteness from the active center. An appropriate substitution pattern provides very active and robust catalysts.

    15. First Synthesis and Characterization by Mass Spectrometry and UV-Photoelectron Spectroscopy of Methylenearsane (pages 873–875)

      Anna Chrostowska, Alain Dargelos, Virginie Lemierre, Jean-Marc Sotiropoulos, Pierre Guenot and Jean-Claude Guillemin

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200352445

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      In a vacuum gas–solid reaction (VGSR; see scheme), the kinetically unstable methylenearsane was synthesized by dehydrohalogenation of gaseous chloromethylarsane on solid sodium carbonate and characterized in the gas phase by mass spectrometry and UV photoelectron spectroscopy. A new approach to theoretically evaluate ionization potentials is also demonstrated.

    16. Doubly N-Fused Pentaphyrin (pages 876–879)

      Alagar Srinivasan, Tomoya Ishizuka and Hiroyuki Furuta

      Version of Record online: 22 JAN 2004 | DOI: 10.1002/anie.200352946

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      Inverted and fused: Meso-pentafluorophenyl-substituted N-confused, doubly N-fused pentaphyrin (see X-ray crystal structure; green: F, blue: N) was synthesized from [3+2] coupling of confused tripyrrane and dipyrromethane dicarbinol, followed by oxidation. Inverted pyrrole rings in pentaphyrin are easily transformed into N-fused tripentacyclic rings.

    17. A Facile Stereocontrolled Approach to CF3-Substituted Triarylethenes: Synthesis of Panomifene (pages 879–882)

      Xinyu Liu, Masaki Shimizu and Tamejiro Hiyama

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200353032

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      The stereoselective preparation and Pd-catalyzed cross-coupling reaction of boronates 2 provides a new general and convenient route to CF3-substituted triaryl ethenes 3, in which the CF3 and Ar3 groups are cis to each other. The synthetic potential was demonstrated by the total synthesis of panomifene (Ar1=Ar3=Ph, Ar2=4-(OHCH2CH2NHCH2CH2O)-C6H4). Bpin=(pinacolato)boryl.

    18. Stereoselective Synthesis of anti-β-Hydroxy-α-amino Acids through Dynamic Kinetic Resolution (pages 882–884)

      Kazuishi Makino, Takayuki Goto, Yasuhiro Hiroki and Yasumasa Hamada

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200353072

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      Upping theanti: Asymmetric anti-selective hydrogenation of α-amino-β-keto esters through dynamic kinetic resolution has been achieved for the first time by using the Ru–binap catalyst. The reaction affords important anti-β-hydroxy-α-amino acids with 74–98 % ee and high diastereomeric ratio in excellent yields (see scheme; binap=2,2′-bis(diphenylphosphanyl)-1,1′-binaphthyl).

    19. Promotion of Fluorapatite Crystallization by Soluble-Matrix Proteins from Lingula Anatina Shells (pages 885–888)

      Ingrid Lévêque, Maggie Cusack, Sean A. Davis and Stephen Mann

      Version of Record online: 22 JAN 2004 | DOI: 10.1002/anie.200353115

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      The geological longevity ofLingula, depicted, suggests that the lightly mineralized carbonate-substituted fluorapatite (FAP) shell has remained well-adapted to evolutionary pressures. Contrary to earlier studies, soluble macromolecules isolated from Lingula shells are shown to specifically promote FAP crystallization by the destabilization of an amorphous calcium phosphate precursor.

    20. The Tertiary Sulfonamide as a Latent Directed-Metalation Group: Ni0-Catalyzed Reductive Cleavage and Cross-Coupling Reactions of Aryl Sulfonamides with Grignard Reagents (pages 888–891)

      Robert R. Milburn and Victor Snieckus

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200352633

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      A mild method for the Ni0-catalyzed hydrodesulfamoylation (see scheme, B) of aryl sulfonamides (1[RIGHTWARDS ARROW]2) with iPr2Mg or iPrMgCl as β-hydride transfer sources can be linked with directed ortho metalation (A and C) to give meta-substituted aromatics 2. Cross-coupling process with alkyl and aryl Grignard reagents furnish disubstituted benzenes and bi- and teraryl compounds.

    21. ortho-Anisylsulfonyl as a Protecting Group for Secondary Amines: Mild Ni0-Catalyzed Hydrodesulfonylation (pages 892–894)

      Robert R. Milburn and Victor Snieckus

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200352634

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      A potentially good alternative to the tosyl group (Ts) as a protecting group for amines is N-ortho-anisylsulfonyl (Ans), which is readily cleaved under mild, Ni0-catalyzed reductive conditions (see scheme, acac=acetylacetonate). N-Anisylation of primary amines followed by alkylation and deprotection provides a route to a range of secondary amines.

    22. Steroids and Steroid Analogues from Stille–Heck Coupling Sequences (pages 895–897)

      Hans Wolf Sünnemann and Armin de Meijere

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200352162

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      Tricyclic 1,3,5-hexatrienes were prepared from 4-substituted 2-bromocyclohexenyl triflate, enantiomerically pure hexahydroindenylstannanes, and tert-butyl acrylate in a sequence of Stille and Heck reactions. In the example shown, an enantiomerically pure steroid with protected functionalities in the 3-, 7-, and 17-positions is formed in a 6π-electrocyclization upon heating at 220 °C.

    23. A General Amination Method Based on the Addition of Polyfunctional Arylmagnesium Reagents to Functionalized Arylazo Tosylates (pages 897–900)

      Ioannis Sapountzis and Paul Knochel

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200353241

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      A one-pot reaction sequence consisting of a Grignard reaction, allylation, and reduction provides new functionalized diarylamines in good yields (see scheme, Ts=toluene-4-sulfonyl, NMP=N-methylpyrrolidine, TFA=trifluoroacetic acid). In the first step azoaryl tosylates, which are readily obtained from aromatic amines, are treated with a myriad of functionalized organomagnesium compounds.

    24. Spatial Screening of Cyclic Neoglycopeptides: Identification of Polyvalent Wheat-Germ Agglutinin Ligands (pages 900–903)

      Valentin Wittmann and Sonja Seeberger

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200352055

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      Affinities enhanced by up to 619-fold were found for new ligands of the plant lectin wheat-germ agglutinin (compared to the binding of N-acetylglucosamine (GlcNAc)). These polyvalent neoglycopeptides were identified from screening of a spatially diverse library of type 1. Binding affinity is determined not only by the number of GlcNAc residues but also by the ligand architecture.

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      Preview: Angew. Chem. Int. Ed. 7/2004 (page 909)

      Version of Record online: 2 FEB 2004 | DOI: 10.1002/anie.200490016